Sludge Watch ==> Tamiflu survives sewage treatment - may cause resistant flu strains

[Maureen Reilly]

Abuse of Tamiflu can create bird flu resistant strains: study
Oct 2, 2007

PARIS (AFP) — Swedish scientists say that Tamiflu -- the frontline weapon in 
any bird-flu pandemic -- cannot be broken down by sewage systems and this 
could help the virus mutate dangerously into a drug-resistant strain.

Countries around the world are stockpiling Tamiflu in the belief it will 
help curb any future outbreak of H5N1 avian flu among humans.

Tamiflu, whose lab name is oseltamivir, is not a cure for flu but can ease 
its symptoms, thus aiding vulnerable patients such as the elderly, and 
reduce the time of illness, thus easing the burden on caregivers.

Scientists led by Jerker Fick, a chemist at Umea University, tested the 
survivability of the Tamiflu molecule in water drawn from three phases in a 
typical sewage system.

The first was raw sewage water; the second was water that had been filtered 
and treated with chemicals; the third was water from "activated sludge," in 
which microbes are used to digest waste material.

Tamiflu's active ingredient survived all three processes, which means that 
it is released in the waste water leaving the plant.

The finding is important because of the risk that Tamiflu, if 
overprescribed, could end up in the wild in concentrations high enough to 
let H5N1 adapt to this key drug, the authors say.

Flu viruses are common among waterfowl, especially dabbling ducks such as 
mallards which often forage for food near sewage outlets.

"The biggest threat is that resistance will become common among low 
pathogenic influenza viruses carried by wild ducks," said co-author Bjoern 
Olsen, professor of infectious diseases at the University of Uppsala and 
University of Kalmar.

These avian viruses could then recombinate with ordinary human flu viruses, 
creating new strains that are resistant to Tamiflu, he said.

"Antiviral medicines such as Tamiflu must be used with care and only when 
the medical situation justifies it," Olsen warned. "Otherwise, there is a 
risk that they will be ineffective when most needed, such as during the next 
influenza pandemic."

The study, published online on Wednesday by the open-access Public Library 
of Science (PLoS), pointed the finger at Japan.

It quoted figures from Swiss maker Roche, which estimated that in the 2004-5 
influenza season, 16 million Japanese fell ill with flu, of whom six million 
received Tamiflu.

At such dosages, the amount of Tamiflu released into the Japanese 
environment is roughly equivalent to what is predicted in areas where the 
drug would be widely used in a pandemic.

Coincidentally, "Japan also has a high rate of emerging resistance to 
Tamiflu," the paper said. A 2004 study published in The Lancet found that 
among a small group of infected Japanese children, 18 percent had a mutated 
form of the virus that made these patients between 300 and 100,000 times 
more resistant to Tamiflu.

http://afp.google.com/article/ALeqM5johTPaZnrC32MSU6WyDgsQL4KcGA